Ingot mold



Oct. 25, 1960 INGOT MOLD W. W. SCHOFIELD ETAL Filed Sept. 26, 1958 INVENTORS WILLIAM W SCHOFIELD WILLIAM OWEN JOHN BIDNER ATTYS.

United INGOT MOLD Filed Sept. 26, B58, Ser. No. 763,731

2 Claims. (Cl. 22--139) This invention relates to molds for casting metal, and, more particularly, is concerned with molds for casting steel ingots with the large end up.

The invention is particularly related to an improvement in the ingot mold disclosed and claimed in our prior US. Patent No. 2,310,553. H

We have discovered that a closer ratio or control between the ingot area and the mold wall area in diiferent portions of the vertical height of the ingot and mold wall is possible, and these areas can be and should be specifically related to the size or area of the ingot mold base.

It is the general object of our present invention to improve upon the ingot mold described in our abovelisted patent by the provision of a mold which is more stable during pouring or transportation, which is less expensive to manufacture, and in which the freezing action of the ingot from the bottom upward is enhanced.

Another object of our invention is to provide an ingot mold of the type described wherein the area of the pedestal of the mold is made in substantially direct proportion to the ratio between the mold wall area and the ingot area at the top of the mold.

Another object of our invention is the provision of an ingot mold for casting ingots with the big end up, and wherein the mold wall is of gradually decreasing thickness downwardly of the mold, and wherein the ratio of lower mold wall area to ingot area is between about .70 and about .90 to 1. i

Another object of the invention is to provide a mold of the type described wherein as the lower mold area is reduced in relation to the lower ingot area from a ratio of about .90 to about .70 to l, the size of the pedestal base is increased in area by an amount equal to about one-half of the reduction in area of the lower mold wall.

The foregoing objects of the invention, and other objects which will become apparent as the description proceeds, are achieved by the provision of a mold for casting an ingot with the big end up, the mold having a wall thickness greater at the top of the mold cavity and of gradually decreasing thickness downwardly of the mold, and having a ratio of mold wall area to ingot area below 1.20 to 1 over the entire vertical height of the mold, the ratio being as low as .70 to l in the lower wall portion of the mold, and an integral pedestal base on the mold, the size of the pedestal having a ratio with the size of the top of the mold in substantially direct proportion to the ratio of the wall area of the top of the mold with respect to ingot area at the top of the mold. Further,

as the lower mold area is reduced in relation to the lower ingot area from a ratio of about .90 to about .70 to l, the size of the pedestal base is increased in area by an amount equal to about one-half of the reduction in area of the lower mold wall.

For a better understanding of our invention reference should be had to the accompanying drawings, wherein Fig. 1 is a front elevation of an improved mold incorporating the principles of the invention;

Patent 1 tion and having an upwardly and outwardly tapering,

cross-sectionally substantially square cavity 12 for casting an ingot with the big end up. It should be noted that the upper end of the cavity 12, usually about the upper 20% thereof, is made with parallel walls 14, the bottom of the cavity 16 being flatly conical and blending in with curved radiuses at 18 to the side walls of the cavity 12.

It is to be further noted that the wall thickness 20 at the top of the mold wall is a maximum, the wall thickness 22 at the bottom of the mold is a minimum, with the'wall 'i thickness gradually tapering from the maximum 20 to the minimum 22.

The area of the ingot mold wall to the area of the ingot mold itself over the entire vertical height of the mold is less than about 1.20 to 1, this ratio being somewhat less than that described in our aforesaid patent. But, moreover, we have discovered that the weight and price of the mold can be materially reduced and the function of the mold enhanced by reducing the ratio of mold wall area to ingot area, particularly at the bottom of the mold to as low as about .70 to 1. Stated more generally, we

particularly contemplate making the ratio of the'lower mold wall area to the lower portion of the ingot between about .90 and about .70 to 1. We have also found that the ratio of the upper mold wall area to the upper ingot area can be reduced to about 1.05 or less to 1.

As aforesaid, the reduction in the mold wall thickness as described materially decreases the weight of the ingot mold and the cost thereof, but it has been likewise discovered that the reduction in wall thickness does not adversely aifect, in fact enhances the cooling of the ingot from the bottom upwardly to reduce the piping in the ingot. This is believed due to the fact that the less amount of metal in the lower wall of the ingot mold tends to avoid storing the heat in the bottom end of the ingot, allows this heat to radiate more easily to the outside air surrounding the mold and speeds up the freezing of the ingot from the bottom end upward. The greater amount of wall thickness and metal in the upper portion of the ingot mold insures that the ingot gradually solidifies from the bottom upwardly and freezes last at the top of the mold.

We have likewise discovered that the stability of the ingot mold of our previous patent is improved, ,both during pouring and subsequent handling if the feet on our previous mold are replaced with a pedestal, and such a pedestal is indicated in the drawing by the numeral 24, this pedestal having a vertical height approximately 10% of the height of the mold. The pedestal 24 is formed integrally with the mold, has a cross-sectional contour similar to the mold, and is made to have an area approximately equal to the area of the mold and ingot at the top of the mold.

Merely by way of example, and without in any sense limiting ourselves thereto, the typical mold illustrated in the accompanying drawings has an overall height of approximately 45 inches, a dimension in the mold cavity of about 22 inches at or near to the bottom of the cavity, a wall thickness of 4% inches near the bottom of the cavity, a mold opening of 26 inches near the top of the cavity, a wall thickness of about 5% inches near the top of the cavity, a length and width of about 37 /2 inches at the top of the cavity, a base 24 about 6 inches high, the base being about 36 inches square, and a total cavity height of about 66 inches.

Completing the mold are u'unnions 26 formed integrally and diametrically opposed on the top or near the top of the ingot mold, and integral gripping claws or lugs 28 formed on the base 24 of the mold, which lugs are used, when required, to help strip the ingot from the mold. "It isimportant that the size of the pedestal 24 of'the mold be correlated with the size of the top of the ingot mold. If the pedestal 24 is made too small then'the ingot mold is top-heavy and is apt to tilt over during pouring or handling. n the other hand, if the pedestal is made too large then it will stick out too'far and ingot molds cannot be stacked close enough together to handle a pair of molds, for example, side by side in a transverse direction on a flat car of the narrow gauge type utilized in a steel mill. In addition, we have found that the size of the pedestal or base of the mold should have a ratio with the size of the top of the mold which depends on the ratio of the mold wall area of the top of the mold with respect to the mold wall area at the bottom of the mold, the ingot area, top and bottom, being unity. More specifically stated, the size of the pedestal has a ratio with the size of the top of the mold in substantially direct proportion to the square root of the quotient of the ratio of the top mold area to top ingot area divided by the ratio of the bottom mold area to bottom ingot area.

By way of example:

Top Bottom 7, Area Area w/Ratlo Pedestal Top Mold Mold] Mold/ Size Size Ingot Ingot 1.04 isto 1. 00 l 02/l.00 as 38.25 is to 37.50" 1.08 is to 1. 00 1.04/LO0 as 39.74" is to 38. 21'. 1.12 is to 1.00 1.05/1.00 as 41.25" is to 38.91" 1.15 is to 1.00 1.07/1.00 as 42.19" is to 39.43

It will be seen from the foregoing ratios that the size of the mold top varies with each mold wall area to ingot area ratio and causes a change in the symmetry of the mold and in the distribution of weight, therefore the size of the pedestal changes to correct for the change in the center of gravity.

The amount of the increase in the size of the pedestal can be again determined in terms of a ratio. Specifically as the lower mold wall area is reduced in relation to the lower ingot area from a ratio of about 0.90 to about 0.70 to 1.00, resulting in a change in proportion to the ratio of the mold wall area to ingot area at the top, the size of the pedestal base is increased by an amount equal to the square root of the quotient of the ratio of the top mold wall area to the top ingot area divided by the ratio of the bottom mold wall area to the bottom ingot area. Utilizing specific examples, the following table can be drawn:

'ltol.

It will be seen from the drawing that the ingot mold of the invention is substantially square in horizontal cross section, with rather sharply but smoothly rounded corners. It should also be understood that when reference is made in the specification or claims to the size of the pedestal in relation to the 'size of. the top of the mold and the top of the ingot that. it isintended that the word size be interpreted to cover their linear dimensions while the word area covers the product of two linear dimensions.

Normally we prefer that the ratio of the mold wall area at the top of the ingot with respect to the ingot area at the top be kept in the neighborhood of'ab'out This is so that the top of the ingot mold will be kept sulficiently thick in the wall so that a man can walk on top of the ingot mold and keep good footing thereon. This is particularly helpful during certain operations upon the ingot molds, for example the placing of hot tops thereof, and the like.

While in accord with the patent statutes one best known embodiment of the invention has been illustrated and described in detail, it is to be particularly understood that the invention is not to be limited thereto or thereby, but that the appended claims define the scope of the invention.

We claim:

l. A mold for casting an ingot with the big end up, said mold being of substantially square horizontal cross section with rounded corners and having a wall thickness greatest at the top of the mold cavity and of gradually decreasing thickness downwardly of the mold cavity, and having a cross-sectional ratio of mold wall area to ingot area below about 1 to 1 in the upper wall portion of the mold, said ratio being about .7 to 1 in the lower wall portion of the mold adjacent the bottom of the mold cavity and gradually increasing upwardly of the mold, and an integral pedestal base on the mold of substantially square cross section with rounded corners, the cross sectional area of the pedestal at its base having a ratio to the cross sectional area of the top of the mold plus the ingot of about 1 to 1, the mold cavity having substantially parallel walls over about the upper 20% thereof, the pedestal having a vertical height approaching 10% of the height of the mold, and the 'side walls of said mold flaring outwardly into said pedestal with an increase in cross-sectional area above said pedestal but below the bottom of the mold cavity.

2. A mold for casting an ingot with the big end up, said mold having a Wall thickness greatest at the top of the mold cavity and of gradually decreasing thickness downwardly of the mold, and having a cross-sectional ratio of mold wall area to ingot area at the top of the mold of less than 1.05 to l, and a ratio at the bottom of the mold cavity of between about .90 and about .70 to 1,

said mold having an integral square base substantially equal in area to the mold and the ingot at the top of the mold, and said sides of the mold being flared outwardly below the bottom of the mold cavity to said pedestal.

References Cited in the file of this patent UNITED STATES PATENTS 

